knowledges

How Is Tungsten Wire Made

2024-01-05 18:00:06

When it comes to tungsten, everyone may be unfamiliar, but when it comes to tungsten wire, you should know it. Tungsten wire is mainly used in electric light sources such as incandescent lamps and halogen lamps.

tungsten wire

Tungsten wire is made of metal tungsten. Tungsten is a kind of non-ferrous metal. It has a heavy feeling when held in the hand. The density of tungsten is 20 grams per cubic centimeter, which is very close to gold. This means that some people use tungsten to forge The reason for gold.

Tungsten is still a very brittle metal. Only when its purity is high, it has plasticity and has great tensile strength, but these are not the main characteristics of this metal. To melt a piece of tungsten, extremely high Temperature, the melting point of tungsten is 3420 degrees Celsius, which is why this metal is used to make tungsten filaments for incandescent lamps.

However, if you let a very thin tungsten wire pass an electric current in the air, it will also break due to overheating, thereby stopping the production of light. This is because tungsten oxidizes at high temperatures and produces tungsten trioxide on its surface, and tungsten oxide The melting point is only 1500 degrees Celsius.

The tungsten calcined at high temperature will produce beautiful colored traces on the surface. This is caused by the different thickness of the oxide film formed on the surface. In the bulb, we see this beautiful oxide film from time to time. This is because in the bulb The oxygen has been pumped away, and a mixture of nitrogen and argon is filled into the bulb. The tungsten filament can emit light for a long time without being oxidized.


In the light bulb industry, the requirements for tungsten filaments are very high. They must be resistant to high temperatures, have excellent high temperature sag resistance, good plasticity, and good electrical conductivity.

There are three types of tungsten wires used in the market, pure tungsten wires, doped tungsten wires and various alloy tungsten wires.

Pure tungsten wire can be divided into paste extruded tungsten wire, colloidal tungsten wire, ductile tungsten wire, etc. according to its performance. Only ductile tungsten wire has better performance and is used more. Other tungsten wires are more easily used due to their brittleness. less.

Doped tungsten wire is to change the poor sag resistance and low luminous efficiency of pure tungsten wire at high temperature. The tungsten wire developed is mainly doped with silicon, aluminum and potassium in tungsten trioxide, which is mainly used for light bulbs and electron tubes. Hot wire.

Alloy tungsten wires mainly include tungsten rhenium alloy wire, thorium tungsten rhenium alloy wire, tungsten molybdenum alloy wire, etc. According to the properties of each alloy tungsten wire material, the place of use is also different.


The raw material of the tungsten wire is ammonium paratungstate, which is a white crystal, slightly melted in water, in a roasting furnace of nearly 700 degrees for 40 minutes, to produce blue crystal tungsten oxide, the particle size is 12-19 microns.

The raw material used in the production of tungsten powder, doped with blue tungsten oxide is for the special requirements of tungsten wire, and doped with aluminum, potassium and other elements to increase the properties of tungsten wire, such as anti-sagging and toughness.

The blue tungsten oxide is reduced into tungsten powder by a hydrogen reduction furnace. The average particle size of this tungsten powder is 2~5 microns. Put the tungsten powder in the mold, and press the billet with an isostatic press, and the pressed tungsten billet Put it into the furnace for sintering, the density of the tungsten bar after sintering is generally 17.7g/cm³.

The tungsten bar is turned into a round rod-shaped tungsten bar for wire drawing after rotary forging, with a density of 19g/cm³ or more. The forged tungsten bar becomes tungsten wire after wire drawing.

Lubricant graphite is added during the drawing process. The diameter of the tungsten wire is 20 microns to 1 mm. The tungsten wire is packaged in a reel.

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